1. Field of the Invention
The present invention relates to a semiconductor probe used for scanning probe microscopy (SPM) and a method of writing and reading information using the same and, more particularly, to a semiconductor probe having a cantilever structure that can adjust a contact force between a tip and a medium and a method of writing and reading information using the same.
2. Description of the Related Art
A probe is used in a variety of SPM technologies. For example, the probe is used in a scanning transmission microscope (STM) for reading information by detecting a current that flows according to a voltage difference between the probe and a sample, an atomic force microscope (AFM) using an atomic force generated between the probe and the sample, a magnetic force microscope (MFM) using a force generated between a magnetic field of the sample and the magnetized probe, a scanning near-field optical microscope (SNOM) improving a resolution limitation caused by a wavelength of a visible ray, an electrostatic force microscope (EFM ) using an electrostatic force generated between the sample and the probe, and the like.
Recently, technology of writing/reading information using the STM has been developed. A recording density of a typical magnetic writing/reading device such as a hard disk drive has dramatically increased for decades. Furthermore, owing to the optimization of a tribology characteristic in an interface between a head and a disc, a high reliability of the writing/reading device is achieved. For example, a recording density of 100 giga (G)bit/in2 is achieved in a longitudinal magnetic recording and recording density above 100 Gbit/in2 is achieved in a perpendicular magnetic recording. However, a magnetic recording technology has a limitation in increasing the recording density due to a superparamagnetic limit. As the SPM that can measure a surface property with a nano-scale using an extremely-sharp probe tip is proposed, it is expected that a recording density of a tera (T)bit/in2 level will be possible. As the recording technology using SPM has an advantage of reducing a size of the writing/reading device, it emerges as a next generation recording technology. However, reliability related to a tribology characteristic in an interface between the probe tip and the recording medium is a technical problem to be solved.
FIG. 1 is a schematic view illustrating a mechanical force that is generated by a bending of a cantilever and functions as a contact force in a probe according to the related art. A probe includes a tip 3 and a cantilever 5. The tip 3 contacts a medium 7 using a bending of the cantilever 5. At this point, a degree of the bending is determined according to a required contact force. For example, when the writing and reading of the information are performed using a semiconductor probe having a resistive tip, a relatively high contact force is required to stably write and read the information using a relatively small amount of a voltage applied.
At this point, when the contact force is determined by only a mechanical force, a problem that arises is that a contact force applied during the writing is identical to that applied during the reproduction. When the contact force increases to realize a stable writing, the tip of the probe may be worn. Particularly, when a ferroelectric such as PbZrTio (PZT) is used as the recording medium, surface hardness of the recording medium is increased. In this case, the wear of the tip further increases. When the extremely-sharp tip is used, contact pressure of the tip with the medium increases. In this case, the tip may be easily damaged and an amount of wear debris increases, causing pollution. There is a finding showing that when the tip is designed to be blunt in a sliding direction, a wear rate of the tip is reduced. However, in this case, the recording density is reduced. Therefore, in order to enhance the contact force of the tip, the design of the tip must be optimized considering the recording density, sliding speed, and material of the medium. In order to ensure wear-resistance of the tip, the tip or medium may be coated with a protecting material such as diamond. Korean laid-open patent No. 1999-069113 discloses a method of using a tip coated with diamond. However, in the writing and reading using the ferroelectric medium, the coating of different material on the tip or medium deteriorates the writing/reading performance. When the bending of the cantilever is determined in response to the contact force that is appropriate for stable writing, the writing and reproduction properties are deteriorated due to the increased wear of the tip. When the bending of the cantilever is determined in response to the contact force that can minimize the wear of the tip, the resulting unstable recording deteriorates the writing/reading performance. Therefore, the contact force between the tip and the medium must be properly determined considering the above problems. However, as described above, when the contact force is determined by only the mechanical force generated by, for example, the bending of the cantilever, a problem arises in that a contact force applied during the writing is identical to that applied during the reproduction. Therefore, it is very difficult to simultaneously satisfy both a condition of a weak contact force that minimizes the wear of the tip and a condition of a strong contact force that enables a stable recording.